Impact of the storage temperature on human plasma proteomic analysis: implications for the use of human plasma collections in research.

PURPOSE: To analyze the impact of storage temperature on the 2D-DIGE profile of human plasma. EXPERIMENTAL
DESIGN: 2D-DIGE and MS were used to identify the differences in the proteomic profiles of aliquots of eight human plasma samples stored at either - 30 or - 80°C for 18 months.
RESULTS: After the depletion of albumin and IgG, 2D-DIGE identified four spots significantly and reproducibly increased, and five spots that were decreased, in samples stored at - 30°C compared with those stored at - 80°C. These nine spots were manually excised, digested ingel and analyzed by MALDI-TOF/TOF. MASCOT database search using the PMF spectra allowed the identification of the proteins present in eight of the nine spots. All the spots corresponded to the complement C3 precursor protein. CONCLUSIONS AND CLINICAL RELEVANCE: Our present results indicate that plasma collections stored at -30°C, and not only those stored at - 80°C, may be used for 2D-DIGE analyses of albumin-and IgG-depleted human plasma without loosing the essential information about highly abundant proteins. This finding expands the applicability of 2D-DIGE to the study of human disease by permitting the analysis of human plasma samples stored at temperatures between - 30 and - 80°C.